This study is designed to re-examine a large geographically defined, well characterized cohort of younger and older onset diabetic persons in southwestern Wisconsin in order to determine the lO-year incidence and progression of diabetic retinopathy, macular edema, and visual impairment. Participants will be examined in their home communities in a mobile examining van. As part of the evaluation, refraction, visual acuity, intraocular and blood pressure measurements will be obtained according to standardized protocols. Determination of urine protein and creatinine, blood glycosylated hemoglobin, and plasma C-peptide levels will be performed. Objective recording of retinopathy by use of stereoscopic fundus photography combined with a standardized protocol for grading the retinopathy will be used. Grading of the stereoscopic photographs will provide a sensitive and reproducible method for detection of the new development or progression of retinopathy and macular edema. The incidence and causes of visual impairment will be determined. The incidence of retinopathy and its various component lesions will be evaluated with respect to risk factors such as: duration and age at diagnosis of diabetes, glycosylated hemoglobin level, blood pressure, measures of renal disease, genetic factors, insulin-like growth factors, serum lipids, plasma C-peptide, and other systemic and ocular conditions as ascertained at the previous examination(s). The vital status of participants will be determined to provide data regarding the relationship between severity of retinopathy and other characteristics and prognosis for life. Data from this study will continue to be used for estimating the need for medical counseling and rehabilitative services, for projecting costs, for measuring temporal trends, for developing causal inferences, for developing preventive strategies, and for designing clinical trials.